1. Field of the Invention
The present invention relates to an automobile seat back and particularly to an automobile seat back structure for protecting cervical vertebrae of a passenger of a subject car when another car bumps into a rear of the subject car.
2. Description of Relevant Art
As an automobile seat back, there is a seat back including a lateral frame member having rotary hinges on front sides of upper end portions of side frames and a portion for receiving pressure when another car bumps into a rear of a subject car as disclosed in Japanese Patent Application Laid-open No. 10-119619, for example.
Therefore, when another car bumps into the rear of the subject car, a forward impact load (first collision) is first applied to the seat back. Then a rearward reaction load (secondary collision) of a passenger is applied. In other words, the load is applied to the pressure receiving portion. At this time, the pressure receiving portion moves rearward. As a result, the lateral frame pivots forward about the rotary hinges on the front sides and a headrest supported by the lateral frame moves to a position corresponding to a head portion of the passenger. Thus, the headrest moves nearer to the head portion of the passenger. Therefore, if the seatback is bent rearward by the reaction load of the passenger in the subject car when another car bumps into the rear of the subject car, the pressure receiving portion instantaneously moves the headrest nearer to the head portion of the passenger by the principle of a lever by the reaction load. As a result, the head portion of the passenger is reliably received by the headrest and the cervical vertebrae of the passenger are protected.
As described above, since a square shape is formed by the side frames and the upper cross member, strength of the seat back is remarkably increased and a problem of deformation of the supporting member body for supporting the pressure receiving portion for receiving pressure of the secondary collision does not occur.
In a state in which the headrest pivots toward the front side to protect the neck of the passenger as a result of the secondary collision, a pivotal motion angle of the headrest toward the front side can be restricted by the stopper face. Therefore, it is possible to avoid generation of a problem of abnormal pivotal motion of the headrest toward the front side.
However, in such relevant art, since the rotary hinges are provided on the front sides, the rotary hinges are recognized as foreign matters when the seat back is pressed from the front side. Since the lateral frame member inclines forward, the member is liable to interfere with shoulder portions of the passenger, the movement of the lateral frame member may be stopped by the shoulder portions, and an amount of the forward movement of the headrest needs improvement.
The present invention has been accomplished with the above relevant art in view and provides an automobile seat back in which a feeling that there is a foreign matter is not provided to the passenger by a position of a pivotal motion center in forward movement of the headrest and the headrest can move forward by an amount corresponding to an amount by which the pressure receiving portion is pushed.
To achieve the object, a first aspect of the invention provides a seatback for an automobile. The seatback has a headrest; a supporting member for supporting the headrest; a pressure receiving member attached to the supporting member, the pressure receiving member has a pressure receiving portion at a lower end thereof for a load to be applied to; and a frame member attached with the supporting member to be pivoted with the headrest.
Preferably, the frame member is a pair of side frames.
Preferably, the frame member is an upper-cross member.
Preferably, the supporting member has a holder fitted with the headrest; and a supporting member body fixed with the holder and the pressure receiving member.
Preferably, the pressure receiving member is configured in a substantially I-shape between a lower end and an upper end thereof.
Preferably, the seatback further has a biasing means for biasing the pressure receiving portion to a front side. The biasing means is to be expanded by a predetermined load.
Preferably, the pressure receiving portion is covered with a cover made of a synthetic resin. The cover has a lock portion. The biasing means is hooked with the lock portion.
Preferably, the upper-cross member has a first stopper face for stopping the supporting member from pivoting when pivoting the supporting member forward.
Preferably, the upper-cross member has a second stopper face for stopping the supporting member from pivoting when pivoting the supporting member rearward.
Preferably, the holder is integrated with the pressure receiving member.
Preferably, the holder and the pressure receiving member are configured together in a substantially L-shape.
Preferably, the holder and the pressure receiving member are configured together in a substantially U-shape.
Preferably, the holder has a straight portion positioned at a central portion of an upper-cross member corresponding to an inside of shoulder portions of a passenger. The straight portion allows a stay of the headrest to be vertically moved. The pressure receiving member is configured in a thin and flat shape and is bent to be placed away from a pad.
Preferably, the upper-cross member is bridged between upper ends of a pair of side frames to be fixed.
A second aspect of the invention provides a seatback for an automobile. The seat back has a headrest; a supporting member having a distal end, a proximal end and an intermediate part, the supporting member being attached with the headrest at the distal end thereof, the supporting member for a load by a pressurizing element to be applied to at the proximal end thereof; and a pivotal element attached to the intermediate part of the supporting member, the pivotal element for pivoting the supporting member thereon with the headrest thereon by the load.
Preferably, the seatback further has a frame disposed between the pivotal element and the headrest. The frame engages with the intermediate part of the supporting member.
Preferably, the frame has a stopper part for the supporting member to be abutted against for stopping the supporting member from pivoting.
Preferably, the stopper part extends toward the proximal end of the supporting member.
Preferably, the stopper part extends in a transverse direction relative to the supporting member.
Preferably, the seatback further has a resilient member biasing the supporting member to an original position with a predetermined force.
Preferably, the resilient member is a spring bridged between a pair of side frames.
Preferably, the seatback further has a cover for covering the proximal end of the supporting member.
Preferably, the cover is made of a synthetic resin.
Preferably, the cover has a lock part. A resilient member is hooked with the lock part for biasing the supporting member to an original position.
Preferably, the supporting member has a flat plate part extending from the proximal end.
Preferably, the supporting member has a collar part enclosing the pivotal element; and a pressure receiving part fixed to the collar, the pressure receiving part extending from the proximal end of the supporting member.
Preferably, supporting member has a pressure receiving part extending from the proximal end; and a supporting body part fixed to the pressure receiving part, the supporting body part supporting the pivotal element.
Preferably, the supporting member has a holder part fixed to the supporting body part and fitted with the headrest.
Preferably, the holder part is integrated with the pressure receiving part.
Preferably, the seatback further has a frame engaged with the supporting member, the frame supporting the pivotal element.
As described above, since a pressure receiving member pivots forward and rearward and a supporting member for supporting a headrest through the upper end pivots forward and backward when the load due to the secondary collision of the passenger is applied to the pressure receiving portion disposed at the lower end of the pressure receiving member, a pivotal motion center is at a frame member, and thus, the feeling that there is the foreign matter is not provided to the passenger. Since the pressure receiving member that pivots with the headrest is in such a position as to be less liable to interfere with shoulder portions of the passenger, the headrest can move toward the front side and it is possible to reliably retain a neck of a passenger.
Since the square shape is formed by side frames and an upper cross member, strength of the seat back is remarkably increased and a problem of deformation of the upper cross member for supporting the pressure receiving portion for receiving pressure of the secondary collision does not occur.
Since an upper end of the pressure receiving member and the pressure receiving portion corresponding to the back portion of the passenger that is a position receiving an impact load accompanying the bumping of another car into the rear end of the subject car form a substantially I shape when viewed from front, an operating plate or the like for receiving pressure is unnecessary to reduce cost and there is only one vertical portion thereby remarkably reducing weight.
Since a pressure receiving portion of a pressure receiving member is continuously biased toward the front side and is disposed behind the biasing means that is not expanded by the load of sitting and is expanded only by an impact load accompanying the bumping of another car into the rear of the subject car, the biasing means is not expanded in response to the load of leaning of the passenger on his/her back in the normal sitting state of the passenger or in the relaxed state and the back can be retained. Since the biasing means can be expanded when the load due to the secondary collision as a result of the bumping of another car into the rear of the subject car is applied, the biasing means does not hinder the movement of the pressure receiving portion and the pressure receiving portion can move reliably.
Even if friction is produced between the biasing means and the pressure receiving portion, frictional sound is less liable to be generated because the cover made of synthetic resin is provided between the biasing means and the pressure receiving portion. Since biasing means is reliably locked by the lock portion formed on the cover, the biasing means is reliably prevented from being detached, however the pressure receiving member is pivoted.
As described above, since the supporting member for supporting the pressure receiving member pivots forward and backward when the load due to the secondary collision of the passenger is applied to the pressure receiving portion disposed at the lower end of the pressure receiving member, the headrest pivots forward and backward through the holder supported by the supporting member. At this time, since the pivotal motion center of the headrest is at the upper cross member, the feeling that there is the foreign matter is not provided to the passenger.
As described above, since a supporting member for supporting a headrest pivots forward and rearward with respect to side frames, the pivotal motion center is at the side frames and a feeling that there is a foreign matter is not provided to the passenger. Since the pressure receiving portion pivots about the upper ends of the side frames when the load due to the secondary collision of the passenger is applied to the pressure receiving portion, the pressure receiving portion is in such a position as to be less liable to interfere with the shoulder portions of the passenger. Therefore, the headrest can move toward the front side and it is possible to reliably retain a neck of a passenger.
Since it is possible to mold of one member, the cost of manufacture can be reduced and a reasonable seatback can be provided.
A pressure receiving portion and a holder are formed separately. Therefore, it is unnecessary to extend the holder to the pressure receiving portion though it is necessary to ensure a size of the holder sufficient to support the headrest. As a result, weight of the holder can be reduced and it is easy to manufacture the holder, and therefore, the cost of manufacture can be reduced significantly. Since the pressure receiving portion need only bear the load due to the secondary collision of the passenger, the pressure receiving portion may be a core and therefore, weight of the portion can be reduced.
Since a pressure receiving portion is continuously biased toward a front side and is disposed behind a biasing means that is not expanded by a load of sitting and expanded only by an impact load accompanying a bumping of another car into a rear of a subject car, the biasing means is not expanded in response to the load of leaning of the passenger on his/her back in a normal sitting state of a passenger or in a relaxed state and the back can be retained. Since the biasing means can be expanded when the load due to the secondary collision as a result of the bumping of another car into the rear of the subject car is applied, the biasing means does not hinder movement of the pressure receiving portion and the pressure receiving portion can move reliably.
Since a first stopper face of an upper cross member comes into contact with a supporting member in response to a load of leaning of a passenger on his/her back in a normal sitting state of a passenger or in a relaxed state, the supporting member does not pivot and a position of a headrest is retained. In a state in which a headrest pivots toward a front side to protect a neck of a passenger as a result of a secondary collision, since a supporting member interferes with a second stopper face of an upper cross member, the headrest does not further pivot toward a front side and it is possible to avoid generation of a problem of abnormal pivotal motion of the headrest toward a front side.
Since a pressure receiving portion and a holder are provided in a position receiving an impact load as a result of another car bumping into a rear of a subject car, and which corresponds to the position of the back of the passenger, and form a substantially U shape when viewed from a front, there are no projections; and consequently, to reduce cost, an operating plate or the like for receiving pressure is unnecessary.
Since a pressure receiving portion and holder are provided in a position receiving an impact load as the result of another car bumping into the rear of the subject car, and which corresponds to the position of the back of the passenger, and form a substantially L shape when viewed from the front, there are no projections; and consequently, to reduce cost, an operating plate or the like for receiving pressure is unnecessary. Since there is only one holder, weight can be reduced significantly.
Since the straight portion does not interfere with shoulder portions of a passenger, an amount of pivotal motion of a headrest toward a front side becomes large. Since a pressure receiving portion is thin in a front-to-rear direction, it is possible to prevent the pressure receiving portion from interfering with knees of the passenger in a rear seat. The pressure receiving portion is liable to receive a load due to a secondary collision of a passenger.